• Electronics and Telecommunications Trends
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• v.36 no.3
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• pp.76-86
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• 2021

Technologies for lithium secondary batteries are now increasingly expanding to simultaneously improve the safety and higher energy and power densities of large-scale battery systems, such as electric vehicles and smart-grid energy storage systems. Next-generation lithium batteries, such as lithium-sulfur (Li-S) and lithium-air (Li-O₂) batteries by adopting solid electrolytes and lithium metal anode, can be a solution for the requirements. In this analysis of battery technology trends, solid electrolytes, including polymer (organic), inorganic (oxides and sulfides), and their hybrid (composite) are focused to describe the electrochemical performance achievable by adopting optimal components and discussing the interfacial behaviors that occurred by the contact of different ingredients for safe and high-energy lithium secondary battery systems. As next-generation rechargeable lithium batteries, Li-S and Li-O₂ battery systems are briefly discussed coupling with the possible use of solid electrolytes. In addition, Electronics and Telecommunications Research Institutes achievements in the field of solid electrolytes for lithium rechargeable batteries are finally introduced.

• Journal of Electrochemical Science and Technology
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• v.12 no.2
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• pp.217-224
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• 2021

In this study, Monte Carlo (MC) simulation is conducted with recurrence relation to study the effect of SiO₂ with different particle size and their roles in enhancing the ionic conductivity and lithium transference number of PMMA composite polymer electrolytes (CPEs). The MC simulated ionic conductivity is verified with the measurements from Electrochemical Impedance Spectroscopy (EIS). Then, the lithium transference number of CPEs is calculated using recurrence relation with the MC simulated current density and the reference transference number obtained. Incorporation of micron-size SiO₂ (≤10 ㎛) fillers into the mixture improves the ionic conductivity from 8.60×10^-5 S/cm to 2.35×10^-4 S/cm. The improvement is also observed on the lithium transference number, where it increases from 0.088 to 0.3757. Furthermore, the addition of nano-sized SiO₂ (≤12 nm) fillers further increases the ionic conductivity up towards 3.79×10^-4 S/cm and lithium transference number of 0.4105. The large effective surface area of SiO₂ fillers is responsible for the improvement in ionic conductivity and the transference number in PMMA composite polymer electrolytes.

• Korean Journal of Materials Research
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• v.32 no.12
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• pp.533-537
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• 2022

Flexible zinc-air batteries have many merits, including low cost, high safety, environmentally friendliness applicability, etc. One of the key factors to improve the performance of flexible zinc-air batteries is to use a gel electrolyte. In this study, gel electrolytes were synthesized from potato, sweet potato, and corn starch. In a comparison of each starch, the corn starch-based gel electrolyte showed the highest discharge capacity of 12.41 mAh/cm² in 20 mA and 6.47 mAh/cm² in 30 mA. It also delivered a higher specific discharge capacity of 7.06 mAh/cm² than the other materials after 100° bending. In addition, the electrochemical impedance spectroscopy (EIS) was analyzed to calculate the ionic conductivity. The potato, sweet potato, and corn starch-based gel electrolytes showed electrolyte resistances (Re) of 0.306, 0.298, and 0.207 Ω, respectively. In addition, the corn starch-based gel electrolyte delivered the highest ionic conductivity of 0.121 S cm^-1 among the other gel electrolytes. Thus, the corn starch-based gel electrolyte was verified to improve the performance of flexible zinc-air batteries.

• Polymer(Korea)
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• v.27 no.4
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• pp.385-391
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• 2003

Lithium p-［Methoxyoligo(ethyleneoxy)］ benzenesulfonates (LiEOnBS) with different repeating unit of ethylene oxide were synthesized and were used for preparing gel-polymer electrolytes. The conductivities and lithium ion transference number were measured as a function of Li-salt concentration and repeating unit of ethylene oxide of the LiEOnBS. The maximum conductivity of the resulting gel-polymer electrolyte was found to be 4.89${\times}$10$\^$－4/ S/cm (LiEO7.3BS, 0.5 M) at 30$^{\circ}C$. The lithium ion transference number (t$\sub$Li$\sub$＋//) measurement were performed by means of the combination do polarization and ac impedance methods in gel-polymer electrolytes. Lithium ion transference number was measured to be in the range of 0.75∼0.92 for the LiEOnBS containing gel-polymer electrolytes. The maximum t$\sub$Li$\sub$＋// was obtained to be 0.92 for the 0.1 M LiEOnBS containing polymer electrolytes. The synthesized LiEOnBS showed single ion transport like characteristics when n was large than 3.

• Journal of Physiology & Pathology in Korean Medicine
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• v.22 no.4
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• pp.968-974
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• 2008

This study was aimed to investigate the electrolytes and its relationship with acute stroke patients in each stroke type by case-control study. 217 patients with first-ever acute stroke within 2 weeks as the case group(Cases), 146 people without four major risk factors(hypertension, diabetes mellitus, hyperlipidema and ischemic heart disease) as the healthy control group(Normals), and 160 people as the general control group(Controls) were recruited at the Stroke Medical Center in Daejeon University Oriental Medicine Hospital from july 2005 to march 2007 for this case-control study. We analyzed the odds ratio of electrolytes in binary logistic analysis and evaluated each stroke type and general characteristics such as age, sex etc. The level of sodium(Na+) and potassium(K+) were significantly lower in LAA, SVO type of ischemic stroke and hemorrhagic stroke. But the level of chloride(Cl-) had no significant relation with stroke occurance. In this study we demonstrated that low sodium(Na+) and potassium(K+) have an influence on stoke occurance than chloride(Cl-). And we think that the electrolytes must be considered in risk factors of ischemic stroke in Korean and more prospective studies are needed.

• Journal of the Korean Electrochemical Society
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• v.19 no.3
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• pp.57-62
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• 2016

The over-discharging phenomena in sodium-nickel chloride batteries were investigated in relation to decomposition of molten salt electrolyte and consequent metal co-deposition. From XRD analysis, the material deposited on graphite cathode current collector was revealed to be by-product of molten salt electrolyte decomposition. In particular, the result showed that the Ni-Al alloys ($Al_3Ni_2$, $Ni_3Al$ and $Al_3Ni$) were electrochemically deposited on graphite current collectors in line with over-discharging behaviors. It is assumed that the $NiCl_2$ solubility in molten salt electrolytes leads to the co-deposition of Ni-Al alloys by increasing metal deposition potential above 1.6 V (vs. $Na/Na^+$). The cell tests have revealed that the composition of molten salt electrolytes modified by various additives makes a decisive influence on the over-discharging behaviors of the cells. It was revealed that NaOCN addition to molten salt electrolytes was advantageous to suppress over-discharge reactions by modifying the characteristics of molten salt electrolytes. NaOCN addition into molten salt electrolytes seems to suppress Ni solubility by maintaining basic melts. The cell using modified molten salt electrolyte with NaOCN (Cell D) showed relatively less cell degradation compared with other cells for long cycles.

• Journal of the Korean Electrochemical Society
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• v.11 no.4
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• pp.242-255
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• 2008

In lithium-ion batteries(LIB), the development of electrolytes had mainly focused on the characteristics of lithium cobalt oxide($LiCoO_2$) cathode and graphite anode materials since the commercialization in 1991. Various studies on compatibility between electrode and electrolytes had been actively developed on their interface. Since then, as they try to adopt silicon and tin as anode materials and three components(Ni, Mn, Co), spinel, olivine as cathode materials for advanced lithium batteries, conventional electrolyte materials are facing a lot of challenges. In particular, requirements for electrolytes performance become harsh and complicated as safety problems are seriously emphasized. In this report, we summarized the research trend of electrolyte materials for the electrode materials of lithium rechargeable batteries.

• Applied Chemistry for Engineering
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• v.10 no.4
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• pp.620-627
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• 1999

Electrochemical properties of the Al current collector being used in lithium ion batteries have been studied in the 4 different aprotic electrolytes(1 M $LiBF_4$ EC : DMC, 1 M $LiBF_4$ EC : EMC. 1 M $LiPF_6$ EC : DMC. 1 M $LiPF_6$ EC : EMC) employing cyclic voltammetry and impedance measurement. Al electrode showed a wide range of the electrochemical window(0.5~4.1 V vs. $Li/Li^{+}$). However, solid interfacial materials has been formed on the Al surface due to reduction of impurities($H_2O$, $O_2$, etc), lithium salts, and electrolytes at low applied potentials, and aluminum oxides in the highly oxidizing potential as well. Especially, Al current collector was susceptible to localized in consequence of impurities in electrolytes.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.465-465
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• 2011

In recent years, electrochemical supercapacitors have attracted much attention due to their high power density, long life cycles, and high efficiency. Some supercapacitors using CNTs have been reported, but there are several issues to be resolved for further development of CNT based supercapacitors. One issue is time consuming procedures to prepare CNT films, which may provide poor control of CNT uniformity over the large area of the substrates. Another is new electrolytes replacing the conventional liquid electrolytes in supercapacitors. In this work, We have successfully demonstrated that spray deposition method of multiwalled CNT films using gel electroytes could be promising for CNT-based supercapacitors on ITO substrates. Specific capacitances using gel electrolyte reached up to 1.5 F/g and 9 mF/$cm^2$, and internal resistance was 28 ${\Omega}$. Specific capacitances and internal resistance of supercapacitors with gel electrolyte were better than or comparable to those with liquid electrolytes($KNO_3$, $Na_2SO_4$), indicating that gel electrolytes could replace liquid counterparts in CNT-based supercapacitors. Combined with gel electrolyte, spray deposition method could provide low cost and easily scalable process for high performance supercapacitors using CNT films on ITO for applications in display devices.

• Journal of the Korean Electrochemical Society
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• v.3 no.3
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• pp.152-156
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• 2000

The effect of cupric ion concentration on the throwing power has been studied in the electrodeposition of Cu on the porous reticular electrodes with the electrolytes of $CuSO_4\;and\;H_2SO_4$. Sulfuric acid electrolytes with lower concentration of $CuSO_4$ improved throwing power in electrodeposition of copper not only due to higher cathodic polarizability but also due to higher conductivity of the electrolytes. The increase in conductivity of the electrolytes at low concentration of $CuSO_4$ could be also illustrated by the decrease in viscosity of the electrolytes. It was found that both the throwing power and the limiting current density should be taken into account in the electrodeposition of Cu on the reticular electrodes. According to the experimental results, the electrolyte of 0.2M $CuSO_4$ and 0.5M $H_2SO_4$ was found to be the most appropriate condition at the current density of $10mA/cm^2$.